The present invention is related to printable adhesive articles. The present invention is especially useful for linerless adhesive tapes and labels. Images and printed matter including indicia, bar codes, symbols and graphics are common. Images and data that warn, educate, entertain, advertise or otherwise inform, etc. are applied on a variety of interior and exterior surfaces.
Techniques that may be used to print images and printed matter include thermal mass transfer printing (also known simply as thermal transfer printing), dot-matrix printing, laser printing, electrophotography (including photocopying) and inkjet printing. Inkjet can include printing by drop-on-demand inkjet or continuous inkjet techniques. Drop on demand techniques include piezo inkjet and thermal inkjet printing which differ in how the ink drops are created.
Inkjet inks can be organic-solvent based, aqueous (water-based) or solid (phase-change) inkjet inks. Solid inkjet inks have a solid wax or resin binder component. The ink is melted. The molten ink is then printed by ink-jet.
The components of an inkjet system used for making graphics can be grouped into three major categories: the computer, software, and printer category, the ink category and the category of receptor medium.
The computer, software, and printer will control the size, number and placement of the ink drops and will transport the receptor medium through the printer. The ink will contain the colorant. The receptor medium provides a repository to accept and hold the ink. The quality of the inkjet image is a function of the total system.
The composition and interaction between the ink and receptor medium is most important in an inkjet system. With printers now exceeding 2400×2400 dpi resolution, inkjet drop size is smaller than in the past. A typical drop size for this dpi precision, is less than about 10 picoliters. Some printer makers are striving for even smaller drop sizes, while other printer makers are content with the larger drop sizes for large format graphics.
Containers, packages, cartons, and cases, (generally referred to as “boxes”) for storing and shipping products typically use box sealing tape, such as an adhesive tape, to secure the flaps or covers so that the box will not accidentally open during normal shipment, handling, and storage. Box sealing tape maintains the integrity of a box throughout its entire distribution cycle. Box sealing tape can be used on other parts of boxes and on other types of article. A typical box sealing tape comprises a plastic film backing with a printable surface and a pressure-sensitive adhesive layer. This tape can be printed and applied to a box to seal the box. It can also be printed, cut into a label and applied onto a box or article. These tapes can be made in roll or pad form, and can have information printed or otherwise applied to, or contained within or on, the tape.
These boxes generally display information about the contents. This information most commonly located on the box might include lot numbers, date codes, product identification information, and bar codes. The information can be placed onto the box using a number of methods. These include preprinting the box when it is manufactured, or printing this information onto the box at the point of use. Other approaches include the use of labels, typically white paper with preprinted information either applied manually, or with an online automatic label applicator.
A recent trend in conveying information related to the product is the requirement to have the information specific for each box. For example, each box can carry specific information about its contents and the final destination of the product, including lot numbers, serial numbers, and customer order numbers. The information is typically provided on tape or labels that are customized and printed on demand, generally at the point of application onto the box.
One system for printing information involves thermal transfer ink printing onto tape or labels using an ink ribbon and a special heat transfer print head. A computer controls the print head by providing input to the head, which heats discrete locations on the ink ribbon. The ink ribbon directly contacts the label so that when a discrete area is heated, the ink melts and is transferred to the label. Another approach using this system is to use labels that change color when heat is applied (direct thermal labels). In another system, variable information is directly printed onto a box or label by an inkjet printer including a print head. A computer can control the ink pattern sprayed onto the box or label.
Both thermal transfer and inkjet systems produce sharp images. With both ink-jet and thermal transfer systems, the print quality depends on the surface on which the ink is applied. It appears that the best system for printing variable information is one in which the ink and the print substrate can be properly matched to produce a repeatable quality image, especially bar codes, that must be read by an electronic scanner with a high degree of reliability.
Regardless of the specific printing technique, the printing apparatus includes a handling system for guiding a continuous web of tape to the print head away from the print head following printing for subsequent placement on the article of interest (for example, a box). To this end, the web of tape is normally provided in a rolled form (“tape supply roll”), such that the printing device includes a support that rotatably maintains the tape supply roll. When the tape roll is linerless, the adhesive of the tape is in intimate contact with the printable surface of the next wrap of tape in the roll.
Examples of microstructured ink receptor media can be found in WO 99/55537, WO 00/73083, WO 00/73082, WO 01/58697 and WO 01/58698.